Plain English Meaning
The last day data can be sent in if it is going to make it into the next published update. Anything that arrives after that day waits for the next round.
Full Definition
The deadline by which new or revised instrument flight procedure data must be received in order to be processed, charted, and published in the next scheduled revision cycle. Information submitted after the cutoff time is held over for the following cycle.
Context Anchor
Seen when reading about how instrument procedures, charts, and navigation databases are revised and published on a schedule.
Derivation
From 'cut off,' meaning to stop or close something at a set point. Here it marks the point at which submissions for a publication cycle are closed.
Why Pilots Care
Missing the cutoff delays incorporation of updated , directly affecting and .